A shape has everything its family has
This is one of the first places your child reasons like a mathematician: if something is true of every rectangle, it is true of every square. That kind of thinking, from a general rule to a specific case, is what geometry proofs in high school are built on. It also clears up a belief many adults still hold, that a square is not a rectangle.
In this video, your child will learn to see what shapes in a family share.
The lesson stops at each question for your child's answer.
Three problems, each a little harder
Each problem is worked step by step. Your child will solve the last one before Bobby shows how.
Example 1
A square is a rectangle. How many right angles does a square have?
Example 2
Every square has four equal sides. A square is a rectangle. Does every rectangle have four equal sides?
Your child's turn
Every parallelogram has two pairs of parallel sides. A square is a rectangle, and a rectangle is a parallelogram. How many pairs of parallel sides does a square have?
The three key steps
- 1A shape has all its family has
- 2Square, rectangle, parallelogram
- 3Not every rectangle is a square
Mistakes to listen for
- Insisting a square is not a rectangle because rectangles have "two long sides and two short sides."
- Reversing the reasoning, so they say all rectangles have four equal sides because squares do.
- Forgetting that a rectangle is a parallelogram, so its parallel, equal opposite sides come as a surprise.
The lesson shows every step, so your child sees why it works. Read our parent's guide to why a square is also a rectangle →
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Questions parents ask
Does my child need an account to watch?
No. You can watch this on any device at any time. If your child would like to practice why a square is also a rectangle, and you'd like parent-friendly reports on your child's progress and growth, you can join Bobby's Math Club for unlimited free practice.
What happens when my child answers a question?
A right answer gets a cheer, and the lesson carries on. If your child isn't sure, they can tap "I don't know yet", and Bobby gives the answer and shows another example. Nothing is scored or stored.
Is this the same lesson that's on YouTube?
Yes. Here, the lesson stops at each question and waits for your child to answer. On YouTube, each question stays on screen for a few seconds, and then the lesson plays on.
Where can I learn more?
There's a short, kid-friendly lesson like this one for every Pre-K to 5th grade math skill, all in our video library. Our parent's guide to why a square is also a rectangle has more on where kids get stuck and how you can help at home. In the club, your child practices at just the right level, about five minutes a day, and you get parent-friendly reports as they grow. Learn more about how it works →
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Questions at your child's level, about five minutes a day, on why a square is also a rectangle and whatever PK-5 skills they need to develop. Unlimited practice, free forever.
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